Add BlimpDocument, pull out functions in BlimpCompositor.

blimp/client/core/contents/blimp_contents_view_impl.cc

Index: blimp/client/core/contents/blimp_contents_view_impl.cc
diff --git a/blimp/client/core/contents/blimp_contents_view_impl.cc b/blimp/client/core/contents/blimp_contents_view_impl.cc
index 28b043a26c12e17ccb162d32025423d38d00a144..f5693145ac7e3b6746348b7b8c0b00471b3db977 100644
--- a/blimp/client/core/contents/blimp_contents_view_impl.cc
+++ b/blimp/client/core/contents/blimp_contents_view_impl.cc
@@ -37,12 +37,12 @@ void BlimpContentsViewImpl::SetSizeAndScale(const gfx::Size& size,
 }
 
 bool BlimpContentsViewImpl::OnTouchEvent(const ui::MotionEvent& motion_event) {
-  return blimp_contents_->compositor_manager()->OnTouchEvent(motion_event);
+  return blimp_contents_->document_manager()->OnTouchEvent(motion_event);
 }
 
 void BlimpContentsViewImpl::CopyFromCompositingSurface(
     const ReadbackRequestCallback& callback) {
-  blimp_contents_->compositor_manager()->NotifyWhenDonePendingCommits(
+  blimp_contents_->document_manager()->NotifyWhenDonePendingCommits(
       base::Bind(&BlimpContentsViewImpl::StartReadbackRequest,
                  weak_ptr_factory_.GetWeakPtr(), callback));
 }